1. Field of the Invention
The present invention relates to an air bag apparatus disposed in a steering wheel of an automobile, an instrument panel or the like in front of the front passenger seat.
2. Description of Related Art
Hitherto, in an air bag apparatus having a pad mounted in a bag holder, a mounting piece portion, which extends from the bottom surface of the pad and is provided with mounting holes, is fixed to the side wall of the bag holder in a state in which the mounting piece portion is fastened between a backplate and the side wall of the bag holder by means of rivets inserted into the mounting holes of the mounting piece portion and mounting holes provided in the side wall of the bag holder and the backplate. The backplate, made of a metal, is disposed to increase the fastening strength of the mounting piece portion against the side wall of the metal bag holder because the pad, including the mounting piece portion, is formed from synthetic resin.
Since the pad is pulled up when the air bag is inflated, a flange which extends toward the backplate is provided in the lower end of the mounting piece portion in order to resist movement of the pad. The flange is brought into abutment with the end surface of the backplate so that the mounting piece portion of the pad is held between the backplate and the side wall of the bag holder (See Japanese Patent Unexamined Publication No. 3-189252).
In the prior art, it is necessary to fix the position of the mounting holes of the mounting piece portion, of the backplate, and of the side wall of the bag holder during a fixing operation using rivets. However, the mounting holes of the mounting piece portion of the pad must be aligned with other mounting holes while pressing a folded air bag during the fixing operation, thereby making the pad likely to shift because it is pushed by the air bag. Therefore, even if the lower end of the backplate is brought into abutment with the flange of the mounting piece portion, the mounting piece portion and the spacer shift horizontally relative to one another, and it is laborious to position the mounting holes.
Since the flange is formed over the entire lower end portion of the mounting piece portion, the mounting holes of the mounting piece portion, to which rivets are fixed, must be arranged in an upper position so that the flange does not interfere with the rivets. Riveting of the mounting piece portion, the backplate, and the upper portion of the side wall of the bag holder makes it likely that interference with devices provided at the pheriphery thereof such as an inflater for inflating the air bag will occur, thus making it difficult to perform riveting.